Machine tool



y ,1 3. c. R. ALDEN MACHINE TOOL Filed March 17, 1932 13 Sheets-Sheet l lwllillulllllllllllll lllllll.

mmv

o .w.\ 3 m,

gt lmlail F nk;

mm m

IW wnm 0 c. R. ALDEN 2,000,553

MACHINE TOOL Filed March 1'7, 1932 13 Sheets-Sheet 2 May ,7, 1935 c. R. ALDEN MACHINE TOOL Filed March 17, 1932 May 7, 1935.

l3 Sheets- Sheet 3 s'icis y 1 I r, c. R. ALDEN 2,000,553

MACHINE TOOL Filed March 17/1932 15 Sheets-Sheet 4 Invenrar c. R. ALDEN MACHINE TQOL Filed March 17, 1932 May 7, 193 5.

l3 Sheets-Sheet 5 May 7,1935. C;"R. ALDEN 2,900,553

' MACHINE TOOL v 1 Filed March 17, 1932 13 Sheets-Sheet 6 N Inward-sf May 7,. 1935.

c. R. ALDEN MACHINE TOOL- Filed March 17. 1932 15 sheets-sheet 7 Invent) Caf677 Rdlldeh MKMW Amer megs c. R. ALDEN May 7, 1935.

MACHINE TOOL Filed March 1'7, 1932 l3 Sheets-Sheet 8 c. R. ALDEN May 7, 1935 MACHINE TOOL Filed March 1'7, 1952 13 Sheets-Sheet 9 May 7, 1935.

c. R. ALDEN MACHINE TOOL Filed March 17, 1932 15 Sheets-Sheet l0 lnvan'i'ar Car r611 Rfllden "W After ragga y 1935- c. R. ALDEN 2,000,553

' MACHINE TOOL Fi led March 17, 1952 13 Sheets-SheetlZ c rat 1304mm Patented May 7, 1935 PATENT" arms MACHINE TOOL Carroll a. Amen, Detroit, Mich" assignor to rai- Cell- Aircraft & Tool Corporation, Detroit, Mich, a corporation of Michiganv Application March 17, 1932, Serial no. 599.4227

46'Clalms.

The present invention relates to improvements in machine tools ,'and has particular reference to a new and improved diamond boring machine. One of the important objects of the present invention is to provide a machine of novel and improved construction in which the work support be machined respectively by two opposed tools 'upon movement in opposite directions and the removal and replacement of one work piece while the other is being machined.

An ther object resides in the respective adjustmentof the opposed tools to take a cut and a finishing cut so thatone or'more ork pieces upon relative movement of the work support in one direction may-be given a roughing cut by one tool,,,and upon relative movement of the support in the oppositedirection may be given a finishing cut by the opposed tool. Further objects reside in the provision of novel means for automatically translating the work support relatively to the tools at arrapid traverse when the tools are not in. operative engagement with the work'and at 'a slow feed when one or more tools are in cutting engagement with the work, and for causing the feed during the finishingcut to be slowerthan during the roughing cut. 1

Another object is to provide a machine tool em no 1 one-or more novel spindle supports, and a'novel relation thereof to the slidable work support and the machine base.

A further object is to provide tary spindle structure.

still another object v vide new and improved means operable automatically in accordance with-the movements of the work support to stop rotation of the tool spindle or group of tool. spindles at either sidewhile the tool spindle or group of tool spindles at the other side are in or are beinsbr sh 111150 9 1 tive relation to the work support.

A further object resides in the novel means for stoppingrointionof. all of the tool spindles whenever the work support regardless of its position or direction of'movement is stopped.

Another object is to provide novel means autoan improved unioperable in accordance with the move- "of the invention isto prce provision of ments of the work support to supply coolantfor the work to the tool or group of toolsat either side while same are in operative relation to the support.

Further objects and advantages will-become apparent as' the description proceeds. v

.In the accompanying drawings, Figure 1 airont view of a machine embodying the features of my invention.

Fig. 2 is a planview. Fig. 3 is a transverse vertical sectional view taken along line 3-3 of Fig. 1.

- Fig. 4 is a fragmentary sectional view, taken along line 4-4 of Fig. 1, of the manual control valve. 1

Fig. 5 is a fragmentary right end view.

Fig.'6 is a fragmentary axial sectional view through one of the spindle fixtures taken along broken line 6-4 of Fig. 5.

view through the table l--l' of Fig. 3.

' Fig. 8 is a diagrammatic, representation of the electric control circuits.

Fig. '9 is a diagrammaticrepresentation of the hydraulic system for the table" and spindle drives, showing the parts in the automatic stop position.

, Fig. 10 is a view similar to Fig. 9, but showing the parts in the positions occupied to effect movement of the tableto the'leit. a

Fig. 11 is a view similar to'Fi g. 10, but showing the parts adjusted to effect a slow feed to the left. i

, Fig. 12 is'a'view similar to Figs. 10 and 11, but with the parts adjusted to effect rapid traverse of the table tothe right. Fig. 13 is an enlarged fragmentary view, pardrive taken along line tially in section, of the hydraulic cpntrol panel.

' Fig. '14 isa composite horizontal sectional view of the panel taken along broken line i l-IE of Fig. 13.

Fig. 15 is a transverse'vertical sectional view taken along line 15-45 of Fig. 14. I

Fig. 16 is a horizontal sectional view taken alongbroken line [6-46 of Fig. 15., v Fig. 17. is an enlarged fragmentary vertical sectional view taken along line lI--ll of Fig. 15.

Fig.- 18 is a' fragmentary view on an enlarged scale of the table control dogs.

' 19 is a fragmentary sectional view taken a1 nguline Isl-l9 of m. 1s.-

' table movement.

Wliile the invention is susceptible; of various modifications and alternative constructions; I

have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form dis elongated hollow base til. Formed on the top of the base 29] are two parallel spaced longitudinal ways 2|, one of which is fiat and the other of which is V-shaped. A table or carriage 22 is formed on the underside with ways 23 mounted on the ways 2! for horizontal translation or reciprocation. The table ways 23 are of such length that they never uncover the base ways 2| at the extreme ends of the table movement. Preferably, the. table 22 is adapted to support the work to be machined, and hence is hereinafter designated as the work table. Hence, the table 22 has a fiat upper mounting pad or surface formed with T-slots id for securing the work or work fixtures in position, and has coolant or water drains 25 at the ends.

Mounted on vone end of the base 28 is a tool I spindle supporting structure 26 in which one or of single or cluster gears.

more spindles 21, extending inwardly over the work table 20 and each provided with-a'suitable metal cutting tool 28, are journ'aled. A similar structure29, rotatably supporting one or more spindles 30 extending inwardly over the other end of the table 22 and in respective alinement with the spindles 21 and each provided with a suitable metal cutting tool 3!, preferably is mounted on the other end of the base 29 so that the table 22 .upon movement in opposite direc-' tions between the structures may bring the work into cooperative, relation alternately with the tools 28 and 3!.

While the'invention in its broad aspects is not limited to any specific type of machine tool, it is particularly adapted to andvhence illustrated in connection with a horizontal diamond boring machine. Such machine is especially useful in accurately boring the wrist pin holes of engine pistons, the ends of connecting rods and the hubs roughing and finishing operations are to be performed, the finishing tools 38 are diamond fly tools while the roughing tools 28 may be cerboloy (tungsten carbide) fly tools, and where only finishing operations are to be carried out,

y Work pieces for one or more or these sets of spindles maybe mounted on the work table 22. Considering any one set of opposed spindles El and as, one or more work pieces may be mounted on the table 22. Thus, it two se te-work pieces are positioned in proper alinement with the dies 27 and 3t, one piece may be machined upon movement of the table 22, in one direction, i. e. to the left into operative relation with the associated spindle 2i, and the other piece 1". r:

= r upon movement or the .1 e in on- Accordingly, where aoo sss posite direction. While one piece is being operated upon, the other finished piece may be repiece or a plurality of alined work pieces may be operated on.

In the present instance, a single engine piston A, having two diametrically alined wrist pin holes B to be bored, and adapted to be mounted,

as by means of a suitable fixture (not shown), on the table 22 between the tools 28 and 3! of each set, is illustrated in such position in Figs. 9 to 12. Movement of the table with the work to the left, causes the tool28 to take a roughing cut in both holes 13, and reverse movement of the table causes the tool 3| to take a finishing cut in both holes.

The two spindle supporting structures 25 and 29 (Eigsfl, 2, 3 and 5) preferably are alike in construction, and hence corresponding parts thereof will be designated by like reference characters. Provided on eachfend of thebase 28, at

the top and respectively along the front and rear base, is an inverted U-shaped bridge member El I which spans th work table-22 transversely of the machine. member 38 is formed along its ends with two par.- allel transverse T-slots 38, .and intermediate the slots with a transverse cored groove 39, and is finished at opposite sides of the latter.v

Mounted on each bridge member 37 are three parallel spindle brackets 40 (Figs.'3 and 6) in etopsurface of each bridgewhich the spindles are suitably journald. Each bracket is provided on the underside with a transverse key or guide M which fits in the groove 39 and is accurately alined'thereby. The brackets t0 arerelatively adjustable along the T-slots 88 so as to obtain the desired lateral location and spacing of the fly tools. In the present instance, an adjusting screw 52 rotatably anchored in the underside of the front bracket 40 is in threaded engagement with the intermediate bracket, and a short adjusting screw 42 rotatably anchored in the bridge member 8? is in threaded engagement with the rear bracket 50, Thus, by means of the screws 42 and t2 the three spindle brackets 6Q on each end may be spaced laterally in the desired relation, and may be accurately located or ed with respects to those on the other end. Suitable bolts 68 1 I t ed in the T-slots 3B are provided for clampmg the brackets to to the bridge member a? in position of adjustment.

Each spindle bracket '40 is formed with a large longitudinal bore 44, finished throughout its length, and is split longitudinally as indicated at '45. Mounted in the bore is a spindle body a motor stator 41 and an outer bearingv he or sleeve 48. The latter projects from one end the bore 64, and preferably houses, two V 1 s w for thespindle. A rotor 49 & on the wlthm the t:

In rigidly mounting the fast revolving spindles in fixed supports, and moving the work table 22 toward and from the cutting tools, a uniform tool spindle extension from the start to the finish of the out, without side play, is obtained. It will be understood, however, that within certain aspects of theinvention, it is immaterial as to which of the tools and the work is stationary and which is movable. 1

While the work table may be driven by any suitable means, preferably an hydraulic drive is pro-- vided. This driv'e is adapted to translate the work table 22 automatically at any desired variation of speeds, as for example at a rapid traverse whenever the tools are not taking a cut, a slow feed during a roughing cut and a still slower feed during a finishing cut, and isalso adapted to maintain constant any predetermined feed regardless of variations in the cutting resistance.

The hydraulic motor (Fig. 7) comprises a cylinder 5i mounted below the work table 22 within the base 20. Reciprocably disposed within the cylinder 5! is a piston' 52 supported by two piston rods 53 which extend slidably through the closed opposite ends of the cylinder 58. Ifreferably, the cylinder 5i is rigidly attached to the underside of the table 22, and the piston rods 53 are secured at their outer ends to the base 20. The opposite ends of the cylinder 5| are connected through the piston rods 53 respectively to two fluid conduits st and 55 leading'to a direction valve 56 (Figs.

The direction valve 56 (Figs. 15 and 16) maybe of any desired construction, and preferably comprises an elongated cylinder bore or valve chamber 5i formed in a valve casing 58 and closed at the ends by means of plates 59 on opposite ends 5t and 55. Two inlet ports 63 and 66 located reof thecasing. A valve piston (ill of the spool type is mounted for reciprocation in the bore ti. Formed in the peripheral wall of the valve bore 5'! are two axially spaced annular ports 5! and 62 connected respectively to the conduits in the valve bore 51 intermediate the ports 6! and 62 is an annular exhaust port 81. The valve piston fit is formed with four longitudinally spaced peripheral collars or heads 68, 69,- i0 and x H defining peripheral spaces 12, i3 and 14.

It will be evident that upon movement of the valve piston to to the left (Figs. 10 and 11), the space it will connect the ports 62 and 64 to supply pressure fluid to the conduit 55 leading to the 'instltuting movementof the worlr't table 22 to the left. Upon reversing the position ofthe valve pistontd (Fig. 12), the spaces and'ilwill re-'- spectively connect the ports BI and 88 and the ports 62 and 6'! to reverse the connection. of.

the conduits-54 and 55 so as to causethe jwork table 22 to travel to the right, 4

range of reciprocation.

mechanism comprises two valves It and II for effecting reversal of the work table 22 respectively to the left and right. The valves 16 and '11 (Figs. 9 to 12) respectively comprise vertical valve bores or chambers 18 and I9 (Fig.'l3) which may be formed in any suitable casings and which in the present instance are formed in a plate or apron so secured to the front wall of the base 20. Slidably disposed in the respective valve bores I8 and 19. are two valve plungers 8| and 82 of the spool type formed respectively with spaced'upper and lower peripheral collars or heads 83 and 84,

and Hand 86 defining ahnular spaces 81 and 88. The upper ends ofthe bores 18 and 119 above the collars 83 and are constantly in communication with a branched conduit 88 adapted "to be connected througha stop valve 90 either to the source of pressure fluid or the exhaust.-

The bores i8 and I9, intermediate thecollars 83 and 84, and 85 and 86, regardless of the posi-- tions of the plungers 8| and s2, arealways in 1 communication with the drain through a branchedexhaust conduit 9!. A cross conduit92 opens at one end to the bottom of the bore 18, and at.

the other end to the side of the bore fisadjacent the top for connection through movement of the head 85 either with the conduit 89 or the exhaust conduit 9 I; Likewise, a cross conduit 93'opens at one end to the bottom of the bore 19, and at the other end to the side ofthe bore 18 adjacent the top for communication through movement of the collar 83 either withvthe conduit 89 or the exhaust conduit 9|. The cross conduits 92 and 93 also open respectively to thejleftand right ends. of the main-direction valve boreB'i.

The bores '18 and 19 (Fig. 13) preferably open 'vertically through the plate 80, and are closed at their lower ends by plugs 94 and at their upper ends by sleeves as through whichthe upper ends of the plungers 8i and 82 slidably extend. It

will be evident that t e lower ends of the plunger-s 1 99 formed in the front of the table 22. The 10- cation and spacing of the dogs 96 and '97 on the table 22 is dependent on'the desired extent and Assuming that the stop valve W is adjusted to connect the conduit 89 to the source of pressure fluid (Figsfldto 12), and that the right-hand plunger 82 is in its uppermost position (Figs. 9 to 11) pressure fluid from the conduit 89 will then be transmitted through the upper end of the valve bore I8 and the cross conduit 93 to the lower end of the valve bore 19 and right end of the direction valve bore 51; and the lower end of the valve bore I8 and left end of the direction valve bore 51 be" connected through the conduit 92, the space 68 and the exhaust conduit 9| 'to the drain. Hence, the plunger. ill will occupy its lowermost position, and thevalve piston: to mill be movedto the left to cause the table22 to travel to the left 1 "As the table 22 reaches its extreme left position, An automatic reset pilot mechanism responsive to the movements of the table 22 is provided tor reve the direction valve 56. The pilot.

the dog 81 "depresses, the plunger 82 (Fig. 11) thereby breaking the exhaust connection from the 4- aoo ssa valve bore. 51; and establishing a connection therefrom to the pressure conduit 89. Thereupon, the plunger BI is elevated into operative position, thereby breaking the pressure connection to the lower end of thebore .19 and the right end of the valve bore 51, and establishing a connection therefrom to the exhaust. As a, result, the valve piston 60 is moved to'the right to reverse the movement of the table 22 (Fig. 12). Upon movement of the table 22 into its extreme right position, the dog 36 depresses the plunger BI, thereby reestablishing the initial connections and resetting the plunger 82.

The stop valve 90 (Fig. 15) is operable automatically or manually to interrupt the translation of the work table 22, and in its preferred form comprises a valve bore-or chamber I opening vertically through the plate 80 between the valves I6 and I1, and closed at the bottom by a plug II and at-the top by a sleeve IN. A valve plunger I02 of the spool type is reciprocably disposed in the bore I 00, and extends upwardly through the sleeve IIII to the top of the plate 80.-

Formed on the plunger I02 are four, longitudinally spaced peripheral collars or heads I03, IM, I05 and I06 which define three annular spaces I01, I00 and I09. The plunger I02 thus constitutes a differential piston which when subjected at both ends to the same pressure tends to assume its uppermost position,

The pressure supply conduit 95 is connected through three parallel branch conduits H0, III and I I2 to the bore I00 respectively at t e upper and lower ends and at an intermediate point. Interposed in the lower branch conduit III is a restricted orifice H3. The exhaust conduit III is connected through two parallel branch conduits II a and M5 to the bore" I00 at spaced points intermediate the conduits IIO, I II and H2. 'A back pressure valve H6 is interposed in the discharge end of the system ahead of the exhaust conduit SI and back of the direction valve '56. Thepressure conduit 89 for the pilot reset valves I0 and I1 is connected to the bore I00 at a point such that when the plunger I02 is in its uppermost position (Figs. 10 to 12), communication will be established therewith through the space I 08 by the main supply conduit 65, and when Qhe plunger is partially depressed (Fig. 9), communication therewith willbe cut oil. Obviously, fully lowering' of the plunger I02 will connect the conduit 89 through the space IIlI with the exhaust conduit 9 I and will therefore cause the ends of the main valve bore 52 to be connected to the exhaust conduit 9| through the valves 16; and TI.

Pressure responsive means is provided for automatically centering the valve piston 6.0 when the-occasion arises. This'means (Fig. 16) comprises twocentering pistons In and H0 slidably disposed respectively in'two bores H9; and I20 formed in the end plates 59, and adapted to engage the ends of the piston 60 when urged inwardly. The outer endsof the bores H8 and I20 the exhaust conduit 9!, and simultaneously to connect the conduit I2I to the supply conduit 65,

the impressed pressure fluid inthe bores IIS and I20 will force the centering pistons II! and H8 into their innermost positions, thus causing selfcentering of the main valve piston 00 (Fig. 9)

to interrupt the conduit connections to the table valve bore I25. A plate I20 serves to close the front end of the bore, and the casing I23 and the plate I26 are secured in assembled relation and in position in the recess I24 by means of bolts IZI. The bore I25 is connected at its inner end to the conduit 89, and is formed at spaced points along its length with annular ports I 28 and I29 connected respectively to the exhaust conduit SI and a conduit I30 opening into the lower end of the bore I00 beneath the stop plunger I02. A valve plunge'r I3I is slidably mounted in the bore. I25, and has a stem I32 extending through the plate I26 and provided with an actuating knob I33. The plunger I38 is formed with a peripheral space I34 adapted either to connect or disconnect the conduits 9i and I30. Obviously,'upon actuating the valve I22 to connect the conduits 9| and I30, the lower end of the bore I00 will be opened to the exhaust, and dueto'be taken upon movement of the work table 22 in opposite directions, 'it is desirable to provide means for automatically stopping the table upon movement thereof after the finishing cut into central or neutral position; This means (Figs. 18 and 19) comprises a. pivotal drop pawl or dog I35 movable with the work table 22, and adapted to engage the upper beveled end of the stop plunger I 02. The dog I35 is pivotally mounted by means of a bolt I36 on a plate I3? secured to the front of the table 22 for adjustment along the T-slot 93. .A forwardly projecting pin I38 on the plate I31 is adapted for engagement in a slot I 39 formed in the right side of the dog I35 to limit pivotal movement of the latter in that direction. The stop plunger I02 and the dog I35 are located forwardly out of range of the reverse-plungers 0| and 82, and preferably for engagement'midway of the work table 22.

It will be evident that the dog I35 is movable to the right past the stop plunger I02 without depressing the latter, but upon movement of the table 22 to the left into the .neutral or loading position, will depress the plunger against the upwardly directed pressure difierential to stop the table. The plunger I02 is not depressed into its lowermost position or sumoiently to release the d a though the slight pivotal movement permitted by the pin I 33 causes the pivotal center to be located tothe left of the plunger. To again institute operation of .the table 22, as for a succeeding cycle, thehand valve I22 is actuated manually to connect the conduits M and. I30, thereby ing the Plunger we to drop into its lowermost position. The dog I35 is thereby Preferably, the

released and drops to the left of the plunger I32.

The valve I22 is now actuated manually to effect return of the plunger I52 to operative position, whereupon the work table 22 is caused to move to the left and through another cycle.

The-work table 22 is adapted to be driven automatically at variable speeds, for example at a rapid traverse when neither of the tools 25 and tent of the table movement to the left and right of the neutral position and the abscissas indicate -flrst hole B; at a slow feed along e-j while the hole B is being rough bored; at a rapid traverse along a--h while the tool 28 is crossing the space between the holes B; at a slow feed alongi-j while the second hole 5 is being rough bored at a rapid traverse along 70-4 just before reversal, then upon reversal to the right, at a rapid traverse along m,--n until the tool 3| is about to contact with the first hole B; at a slow feed along o--p while: the hole B is being flnishedbored; at a rapid traverse along q---r while the tool II is crossing the space between the holes B; at a slow feed along s-t while the second hole B is bein finish bored; at a rapid traverse along line u-v until reversal; and flnally upon a reversal to the left, at a rapid traverse along w--c to the initial starting position. It will be noted that on the final traverse in each direction, the tool is caused to move slightly beyond the work before reversal so as to afford time to stop the tool before commencing withdrawal past the center position. Preferably, the intermittent feeds to the right -during the finishing cuts are somewhat slower than the corresponding roughing feeds to the left. While the table movements have been described as applied to a particular type of work piece, it will be understood that the programming of the table 22 may be varied to suit any desired problem without departing from the spirit and scope of the invention.

In the present instance, the impelling fluid pressure is maintained constant, as for example by means of a pressure relief valve I40 interposed in a branch conduit I4I from the main supply" "(Figs 15 and 16) to which the exhaust fluid from .Lthe direction valve 56 is directed. The --speed valve I42 preferably comprises a bore or chamber I43 which is formed inthecasing 53 in parallel relation to the bore 51 and suitably closed at the ends. The exhaust-part5! of the maiir'valve 55 opens in the peripheral wai'Ipf-the bore I43 and constitutes the inlet port for the valve I42. Two

annular discharge ports I44 and I45 are also.

formed/in the bore I43 respectively, at bpposite sides of the port 51.

Beoiprocably disposed in the bore m is a we piston I45 of the spool type formed with an annular peripheral space I41 which is adapted upon movement of the piston respectively into opposite end positions to connect the inlet port 51 either to the discharge port -I44 or the discharge port I45. The port I44 communicates with a, substantially unrestricted discharge passage I43 connected to the exhaust conduit 9|, while the port I45 is connectedthrough a passage I43 with means hereinafter described for restricting the flow of fluid. It will be evident that with the piston I45 in its left-hand position, the table 22 will be movable at a rapid traverse, and that with the piston I45 in the opposed position, the table will be movable at a slow feed.

A reset pilot mechanism (Fig. 13) consisting of a traverse valve I and a slow feed valve I5I is provided for automatically actuating the piston 545 of the speed valve I42. The valves I and I5I preferably are built into an integral structure with the reverse and stop valves l5, l1 and 90, and hence respectively comprise vertical bores or chambers I52 and I53 opening through the plate 35. Of the bores I52 and I53, the lower ends are closed by plugs I54 and the'upper ends are closed by sleeves I55. Slidably disposed in the respective bores I52 and I53 and extending upwardly'through the sleeves I55 are two valve plungers I55 and I5! of the spool type formed respectively with longitudinally spaced peripheral collars or heads I58 and I58fand I50 and i 5!, de-.

fining annular spaces I52 and I63, The upper ends of the plungers I55 and I5! above the plate 89 are beveled to constitute abutments alternately responsive to the movements of the work table 22. The pressure conduit 89 opens to the upper ends of the bores I52 and I53so that pressure .fluidacts constantly on the upper heads I58 and I 60.

The exhaust conduit 3| opens tothe bores I52 and J53 constantly in communication with the spaces I52 and I63 for all positions of the plungers I56 and I51. A cross conduit I64 opens from,

the bore I52 adjacent the upper end to the lower end of the bore I53 and right end of the speed valve bore I43, and is adapted to be brought into communication either with the pressure conduit 59 or the-exhaust conduit 5i upon movement of thepl unger'I56respectively into its lowermost or uppermost position. Likewise, a cross conduit I65 opens from'the bore I53 adjacentthe upper end to the lower end of the bore I52 and the left end of the speed valve bore I43, and is adapted to be connected either with the high pressure"conduit 89 or the exhaust conduit sl upon movement of the manger I51 respectively into its lowermost or uppermost position.

The plungers I58 andli'l by reason of their pistonswhich will seek their uppermost positions when both eiids are subjected to the high pressure in the conduit 89. It will be evident, that when the traverse plunger I56 is depressed, high pressure will be transmitted to both ends of the bore I53 and to the right end pf the valve bore I43, thus positioning the valve piston I45 (Figs. 9 and ---i,q) to effect rapid traverse of the work table 22 in adirection depending on the valve 56. The plunger I57 will occupy its uppermost position,

- upwardly projecting endsconstituteiiii'erential thereby connectng the lower end of the bore I52 andthe left end of the valve bore I43 to the ex- ,haust conduit 3|. If the feed plunger I51 is now depressed, the pressure conduit 89 will be connected to the lower end of the bore I52 and'the left end of the bore I43. 'I'hereupon the traverse and therethrough will connect the lower end of the bore I53 and the right end of the bore I43 to the exhaust conduit 9I so as to establish the plunger I51 in its lowermost position andeffect 5 movement of the piston I46 to the right (Figs. 11

" 22 for actuating the plungers I56 and I51.

I68 and I69, pivotally mounted respectively onplates I19 adjustably secured to the front of the table 22 along the T-slot 99, are located between the dogs I66 and I61, and are adapted respectively to depress the traverse plunger I56 to institute rapid traverse of the table 22 while the tools 28 and 3| successively are crossing the space between the holes B of the work piece A.

The dog I66 is limited against pivotal movement to the right past verticahposition through engagement of a slot llftherein with a pin I12 on its plate I18, but is free to pass over the w/plunger I56 upon movement with the table 22 to the right. Likewise, the dog I69 is limited against pivotal movement to the left past vertical position through engagement of a slot I13 therein with a pin I14 on its plate I18, but is free to flip over the plunger I56 upon movement with the table 22 to the left.

Four additional drop dogs I15, I16, I11 and I18 are pivotally mounted respectively on plates I19 adjustably secured to the front of the table 22 along the T-slot 99 and between the reversing dog 91 and the stop dog I35. The two dogs I15 and I16 on the right have pin and slot cormections I88 with the respective plates I19 preventing pivrotalgmgvement to the right past the vertical, and

It will be evident that fluid discharged from the port I in passing through one or both of the orifices I9ll and I9I will be subjected to the flow law of orifices, and will therefore build up a back pressure checking the speed of the'table 22 to a predetermined point. The pressure varies as the square of the volume of the fluid flowing through the orifices, and hence increased flow cannot take place unless the rate of travel of the table 22 is increased. The velocity of fluid flow through the orifices thus is proportional to thelrate of travel of the table 22. The orifices serve to prevent any appreciable fluctuations in the predetermined slow speed of the table 22 otherwise tendingi-o result from variations in resistance to the cutting action. It will be evident that the rate of feed is dependent upon the sizes'of the orifices employed, and that different rates of feed may be obtained by selectively varying the number of orifices, of the same or different sizes, connected in parallel at any one time. Obviously, the number, sizes and combinations of orifices can be indefinitely multiplied to obtain a wide and finely graduated range of feed adjustments.

Preferably, a slower feed is employed during the finishing cuts than during the roughing cuts. The orifice I98 which is intended to produce the slowest feed that may be desired in either direction of table travel is constantly connected to the discharge port I46. To obtain a slightly faster feed during the roughing cut, the restricted oriflce I 9 I is brought automatically into parallel with the orifice I98 (Figs, 9 to 11) -The connection of the orifice I9I into'or out of communication with the port I45 is automatically controlled by means of an orifice control valve I92 (Fig. 1'7) which comprises a valve piston I93 slidably'disposed in the bore I86. The piston I93 is formed with a peripheral annular space I96 always establishing communication between the passages I59 and I89, and adapted when in its left-hand position also to connect the passage I85 with the passage I99 so 1 as to obtain a faster feed.

The piston I93 is automatically moved from 45 are adgfitd\tp\successively depress the feed one position to the other upon each reversal of plunger I51 upon movement of the table 22 to the left to institute the slow feed while thelogl 28 is travel of the table 22. The pressure impulses argwlgad through the conduits 92 and 93 p r in n t w rk h l s B. Th wo dog? I T which o enfispectively to the left and right ends and I18 on the left have pin and slot connections I'8I with the respective plates I19 limiting pivotal movement past the vertical to the left, and are adapted to depress the feed plunger I51 upon movement of the table to the righltoeffect a slow feed successivelyfor' engagement of the tool 3| with the holes B in the work A. x

To provide means for restricting the discharge of exhaust fluid from the valve I42, so as to reduce the speed of the work table 22, the discharge passage I49 is adapted to be connected through an orifice or various combinations of orifices to the exhaust passage I48. To this end, a plurality of chambers or bores I82 (Fig. 17') two in the present instance, are formed in the bottom of the casing 58. The chambers I82 are interconnected by a passage I83 which is connected to the exhaust passage I48. The inner ends of the chambers I82 are connected respectively through spaced passages I 84 and I85 to a transverse chamof the bore I86. Thus, when the reverse plunger 8| is depressed to institute movement of the table 22 to the left, pressure fluid is supplied to the conduit 93 and acts to move the piston I93 to the left, thereby cutting in the orifice I9I, to obtain a relatively fast feed during the roughing stroke (Fig. 11) Conversely, upon depressing the plunger 82 to reverse the movement of the table -22 .to'the right, the conduit 93 is connected to the exhaust conduit 9|, and pressure fluid is supplied to the conduit 92 and acts'to move the piston I93 to the rightfthereby cutting out the orifice 'I9I to obtain a slow finishing feed (F g. 12).

Preferably, the plate or apron 88 constitutes a control panel secured in the front wall of the base 29. Cover plates I95 and- I96 are secured to the front and rear faces of the panel 88. A bracket I91 supporting the casing'58' on its underside is secured against rear or inside facejf plate. I96. The passages serving the various v alve units are formed mainly in the contacting surfaces of the -parts 80, I95," I96, I91 and 58. Thus all of the valves are built into an integral hydraulic structurewhich may be readily demounted as a unit from the machine by merely removing the plate 89. A cover plate I98 is secured to the base below the plate 88 to enclose the casing 58.

To prevent withdrawal of the tools from causing spiral marks in or otherwise marring the bored surfaces, the spindles 30 are stopped and braked during movement of the table 22 to the left, and the spindles 21 are stopped and braked during movement of the table to the right.

Rotation of the spindles 21 and 30 is controlled respectively by a normally open switch I and a normally closed switch 200, and by a master switch 20 I. The details of these switches form no part of the present invention, and are therefore not specifically described. A manually controlled switch 20I' is-adapted to connect mains Ll, La, and L: (Fig. 8) to lines 202, 203 and 204 H1 motor 205 mounted on the rear of the machine for driving the pump 00.

The switch I00 controls a circuit from the line 203 to the line 204 including a solenoid 200. when energized, the solenoid 200 serves to close a switch 201 to connect the lines 202, 203 and 204 to the driving motors 41, 40 for the spindles 21 at the left end of the machine. Likewise, the switch 200 is pted to close a circuit from the line 200 to the line 2M including a solenoid 200. Upon being energized, the solenoid 200 is adapted to close a switch 209 for connecting the lines 202, 200 and 204 to the driving motors 41, 00 for the spindles 30 at the right end of the machine.

The master switch. 20l is interposed in the circuit between theline 200 and the switches I00 and200, and is adapted to be controlled automatically. i. e. to be closed when the table 22 is set into operation and opened when the table is stopped. Thus, the switch 20l has an actuating stem 2!!! adapted to assume either an "on" or "oil'" position. The actuating stem 2I0 is secured to a piston 2i I slidably disposed in a cylinder 2 It mounted on the rear of the base 20 of the machine. Opposite ends of the cylinder 2I2 are connected to the conduits 00 and HI. It will be seen that when the stop plunger I02 is lowered to stop movement of the table 22 (Fig. 9), pressure fluid will be supplied through the conduit I2I to the right end of the cylinder 2| 2, and the other end of the cylinder will be connected through the conduit 80 to the exhaust, so as to move the pistone2i I into the "off position, thereby stopping the motors for the spindles 21 and. 00, and that upon movement of the stop plunger I02 into its operative position to connect the conduits 00 and I2I respectively to the pressure side of the systemand the exhaust, the piston 2 will occupy its on" position to permit operation of the spindles 21' and 30.

The spindle switches I00 and 200 (Fig. 6)

tively for the left-hand and right-hand groups of spindles 21 and 30 have actuating t ms 2I3 and 2M and are mounted at opposite 2H8 hasacrankarmfisconnected fihroush Mink 2210 to a rod 22L piston 2122 slidably disposed in a cyl n Secured tothe IS a mounted on the rear of the bridge menl Opposite ends of the cylinder 223 are conne to the conduits s4 and 5s. Thusfupon instit i ing movement of the table 22 to the left, the piston 222 will be moved to the left asviewed in Figs. 9 to '11, thereby rocking the shaft M0 to to the switches I00 and 200 and alsoto a the stems in engagement withopen the switch 200 and close the switch I00.

Thereupon'. the left-hand group of spindlesz'l will be in operation, and the right-hand group of spindles 00 will be idle. Upon movement of the table "to the right, the switch 200 will be closed and the switch I00.'will be opened to effect operation of the spindles 20 and stop operation of the spindles 21.

The braking mechanism in its preferred form (Figs. 2, 5 and 6) comprisesa-brakeudrum- 224 on the outer end of cache! the spindles 21 and 30. A brake band 225 anchored at one end to the associated spindle bracket 40 embraces the drum 224 and is secured at its other end to the upper end of a vertical lever 228 pivoted intermediate its ends on the associated spindle bracket. The

. lower end of the lever 220 is forked, and the forks of the three levers orieach end of the machine are laterally alined. Extending slidably through the forks of each set of levers 220 is an actuating rod 221. Two spaced collars 220 and 220 are secured on each rod 221 at opposite sides of each lever 226. A coiled compression spring 230 is disposed on each rod 221 in end abutting engagement-with the foremost collar 220 and the lower end of the associated lever 226. Thus, upon moving either rod 221 rearwardly. pressure will be stored in-the associated springs 230 and the lat-. ter will thereupon actuate the associated levers 220 to apply a braking action to the associated set of spindles 21 or 30.

The shifter rod 221 on the right end is actuated in opposite directions in accordance with hydraulic unit (Fig. 2) comprising a cylinder 232 in parallel with the cylinder 222 and a piston 233 disposed therein. The piston 233 is operatively connected through a rod 234, a link 285, a crank arm 230, arook shaft 231 and a crank arm 23! to the front end of the left hand rod 221. It will thus beevident that when the table 22 is impelled to the left (Figs. 9 to 11), the pistons 222 and 232, will each occupy its left-hand position so as to brake the spindles 00 on the right end of the machine, and to release the spindles 21 on the left end of the machine. Conversely, upon movement of the table 22 to the right (Fig. 12), the

pistons 222 and 282 will occupy their right-hand positionsto brake the spindles 21 on the. left end of the machine and to release the spindles 30 on .the right end of the machine.

Another feature of the invention resides in providing coolant to the spindles during their operation. The coolant from any suitable source (not shown) is supplied to a.pump 230 preferably of the gear type which is driven by the motor 205 and which discharges to the cylinder 240 of a coolant valve 2lI"(Fig. 9). Opening in spaced relation from the'cylinder 240 are two coolant conduits 242 and 243- leading respectively tothe spindles 21 and 30 at opposite ends of the, machine. The conduits 242 and 24 3 are connected to cored passages M 'in the spindle brackets 40. The coolant in flowing through these passages serves to maintain the spindle bearings at a substantially constant temperature, the eoy insuring accuracy and precision uring the cutting operation. A valve piston 26% 3f awn type formed with two longitudinally 

